'Firewall Guide' has been marked for removal and could be merged with the 'Firewall Configuration' page that is not marked for removal. A page with a title such as 'Firewall Guide' may be an appropriate location for a section to introduce ufw as a simple alternative for less advanced users. Hence the section on ufw firewall is temporarily inserted there. It can be modified or removed if it is inappropriate.
Perhaps this 'Firewall Guide' could be merged, as a temporary solution, with the 'Firewall Configuration' page so that four configurations are offered in total - the two configurations from this page plus the two from 'Firewall Configuration': nftables, 2 x iptables, ufw. An introductory paragraph might be added then? For example, "The following are four possible firewall configurations among others." Perhaps entitle the section with this page's ('Firewall Guide') iptables configuration 'Simple iptables configuration'; and entitle the iptables section in 'Firewall Configuration' 'iptables configuration for IPv4 and IPv6'? - GreattoBeGrateful 27.8.2017